This invention relates to an electric blower motor and, more particularly to an electric blower motor having an interconnected electric heating element for eliminating condensation, frost or the like on windows of motor vehicles, e.g. a rear window of a convertible top. The blower motor includes a circuit which has a relay.
A known electric window defroster system for a motor vehicle is disclosed in German Patent Document DE-OS 37 19 639 in which a heating resistor, by way of a control unit and a relay, is supplied with operating current only when a voltage is fed to a connecting line of a fan motor.
There is needed a circuit for an electric blower motor, including an electric heating element, which has a simple construction and, still stands out due to its high operational reliability.
The present invention meets this need by providing an electric window defroster system having a circuit formed by a first relay for the control of the blower motor and a second relay for control of the heating element. The second relay is connected to a connecting terminal of the blower motor via a line of a control circuit.
The advantage of the present invention is that the electric heating element is safely switched off in the case of disturbances in the control or load circuit of the electric blower motor. Overheating of the heating element proper, or of adjacent parts, is prevented in this manner.